Why is this happening?

I have some reverb "automation" with bus envelops... I play around a little (maybe when I replace the nested project with an updated version) and BAM my envelopes disappear... not very much fun to keep recreating them thinking it was a fluke!

I don't touch those tracks at all! (the nested project is a seperate layer).

*edit* Mind you, the volume envelope on another track stays just fine (including the edits to it).